In recent years, as an information recording medium, various mediums, such as a DVD (Digital Versatile Disc), a Blu-ray (Registered Trademark) disc, and a flash memory, are used. In particular, a memory card, such as a USB memory with a large-capacity flash memory mounted therein, is widely used in these days. A user records contents, such as music or a movie, on various information recording mediums and loads the mediums in a reproducing apparatus (player) to reproduce the contents.
Recently, contents are actively distributed through a network, and the form of content purchase processing by the user is gradually shifted from purchase processing of disc with contents recorded thereon in advance to processing for downloading contents from a server connected to a network.
As a specific content purchase form, for example, there are the following content purchase forms, in addition to processing for purchasing a medium, such as a ROM disc.
(a) EST (Electric Sell Through) in which a user apparatus, such as a terminal or a PC which is connectable to the network, is used and connected to a content providing server to download and purchase contents.
(b) MoD (Manufacturing on Demand) in which a shared terminal installed in a public space, such as a convenience store or a station, is used to record contents on a medium (memory card or the like) of the user.
As described above, if the user has a medium, such as a memory card for recording contents, the user can freely select and purchase various contents from various content sources, such as content providers, and can record the contents on his/her medium.
The processing of EST, MoD, or the like is described in, for example, JP-A-2008-98765.
However, copyright, distribution rights, or the like of much content, such as music data and image data, are possessed by a creator, a seller, or the like. Thus, when providing contents to the user, control is performed such that there is a certain degree of use restriction, that is, only a user who has regular use rights is licensed to use contents and unregulated use, such as unpermitted copy, does not occur.
Specifically, when the user downloads contents, such as a movie, from the server and records the contents on a recording medium, such as a memory card of the user, for example, the following processing is performed.
The server provides contents to a client (user apparatus) as encrypted contents.
A key for decrypting the encrypted contents is provided only to a user who performs regular content purchase processing.
The content provision processing is performed to realize control of the use of contents.
However, even when the above-described processing is performed, for example, it is difficult to prevent a user who performs regular content purchase processing from providing the key for content decryption acquired from the server to another person. Specifically, there may be assumed a case where the key acquired from the server is put on a network or the like and set in a state of being usable by an unspecified number of people. If this action is carried out, anyone can decrypt, reproduce, and use the encrypted contents using the released key, and the unauthorized use of contents becomes widespread.